Palestinian residents said the Israeli forces crossed the border in the area of the town of Beit Hanoun, in the northeastern corner of Gaza, opposite the Israeli town of Sderot, a frequent target of Palestinian rockets.

The Israeli vehicles were positioned in Palestinian farmland outside the town, the residents said.

he Gaza offensive, aimed at recovering a captured soldier and stopping armed groups from firing makeshift rockets, has piled pressure on the Palestinian government led by Hamas, which demands a prisoner swap for the Israeli corporal.

Israeli tanks and armored personnel carriers, backed by helicopters with machine guns sending down bursts of fire, moved into farmland near Beit Hanoun, an area often used by militants for launching rockets.

Small groups of militants opened fire at the Israeli forces, but there was no report of casualties.

"There is an army activity in Beit Hanoun. There has been deterrent fire," said one Israeli military source.